The definition of the historic(al) episcopate is to some extent an open question by some. For example, Bishops of the Evangelical Lutheran Church in America lay claim to the apostolic succession through the laying on of hands by bishops of the Episcopal Church, which is the U.S. Province of the Anglican Communion.[1] Some theologians, such as R.J. Cooke, have argued that the Methodist Church is also within the historic episcopate, being "in direct succession to the apostles through the bishops and patriarchs of the Eastern Church".[2]An Anglican-Methodist Covenant stated that

Anglicans and Methodists are aware of the substantial ecumenical consensus that recognises that ministry within the historic episcopate should be a feature of united churches (as it already is of several in South Asia with whom Methodists and Anglicans are in communion).[3]

The Roman Catholic Church holds that a bishop's consecration is valid if the sacrament of Holy Orders is validly administered with the intention of doing what the Church does by ordination and according to a valid sacramental form, and if the consecrating bishop's orders are valid, regardless of whether the rite takes place within or outside the Roman Catholic Church. Thus, Roman Catholics recognize the validity of the episcopacy of Eastern Orthodox, Oriental Orthodox, Assyrian Church of the East and Old Catholic bishops, but argue the validity regarding Anglican bishops and Independent Catholic bishops (see Episcopi vagantes).

The Eastern Orthodox Church's view has been summarised as follows: "While accepting the canonical possibility of recognising the existence (υποστατόν) of sacraments performed outside herself, (the Eastern Orthodox Church) questions their validity (έγκυρον) and certainly rejects their efficacy (ενεργόν)"; and it sees "the canonical recognition (αναγνώρισις) of the validity of sacraments performed outside the Orthodox Church (as referring) to the validity of the sacraments only of those who join the Orthodox Church (individually or as a body)."[4] This applies to the validity and efficacy of the ordination of bishops and the other sacraments, not only of the Independent Catholic Churches, but also of all other Christian Churches, including the Roman Catholic Church, Oriental Orthodoxy, and the Assyrian Church of the East.

The Eastern Orthodox position on Anglican orders (in the hypothesis of Anglican bishops joining the Orthodox Church individually or as a body) is controversial, involving disagreements among national churches, theologians, and bishops. Because of changes in the Ordinal (the rites of Holy Orders) under King Edward VI, the Roman Catholic Church does not fully recognize all Anglican Holy Orders as valid, but the latter are recognized (and participated in) by Old Catholics, whose Holy Orders are considered valid by Rome.

Lutheran and other episcopally ordered Protestant successions are not recognized by Roman Catholics.

More than 95% of the world's more than 5,000 living Western bishops in the Roman Catholic Church, trace their episcopal lineage back to 16th century bishop Scipione Cardinal Rebiba. In the early 18th century, Pope Benedict XIII, whose orders descended from Rebiba, personally consecrated at least 139 bishops for various important European sees, including those in Germany, France, England and the New World. These bishops in turn largely consecrated new bishops in their respective countries, effectively erasing other episcopal lines.[5][6]

In the sixteenth century a solid body of Anglican opinion emerged which saw the theological importance of the historic episcopate[a] but refused to 'unchurch' those churches which did not retain it.[7] The preface to the Ordinal limits itself to stating historical reasons why episcopal orders are to 'be continued and reverently used in the Church of England'.[8] Before 1662 it was assumed that the foreign Reformed (Presbyterian) Churches were genuine ones with an authentic ministry of Word and Sacrament. The 1662 Act of Uniformity formally excluded from pastoral office in England any who lacked episcopal ordination but this was a reaction against the abolition of episcopacy in the Commonwealth period.[9]

As the divergences between the theory of 'the godly prince' and the practices of monarchs like James II, William III and the early Georges became more obvious, Pearson[b] and Beveridge[c] saw the "Apostolical Office" of the bishop as a guarantee of the Church's identity and this formed the back-ground to the vital emphasis placed on it by Newman and the other Tractarians,[10] through whom it passed into Anglo-catholic thought.

The modern debate divides three ways: between those who see the 'Historic Episcopate' to be constitutive of the Church (of the esse); those who hold it is a question of its "well-being"(bene esse); and those who consider that it is necessary for the Church to be fully itself (plene esse).[11] The "Chicago-Lambeth Quadrilateral" includes the "historic episcopate" as "essential to the visible unity of the church", but allows for its being adapted locally in its working to the varying needs of those who God calls into the unity of the Church.[12] However, this has not meant a general commitment to the idea that in its absence there is no Church.[11]